I've been thinking to myself why don't I just go ahead and toss the processor on a board and do what I want, but load the arduino bootloader on it ?

I'm in the process of hunting down a box from polycase, probably won't make it water-proof the first go around and max it out. Maybe engineer another one to fit into a larger box, water-proof, with the arduino header still there to use other shields and what not.

Thoughts ?

AMP2 Corinthians 8:21For we take thought beforehand and aim to be honest and absolutely above suspicion, not only in the sight of the Lord but also in the sight of men.

I do think it would be nice to have at least the VR sense chip and CAN bus on the same board as the processor, which would make it possible to have a 'breakout board' sitting on top with no chips, but perhaps a few voltage dividers, current limiters and output drivers.

But if you're going through the trouble, why not go with a whole other processor that's still Arduino capable? Just one of a million would be the Intel Edison chipset, or an ARM processor

Of course all this will add to the cost... I was thinking of making a breakout board for the Arduino Mega so it would be easier to connect everything to rather than re-engineer the base board to fit my needs.. I think I came up with a $200 bill for a 4x6" dual sided board when I got 4 printed at once... then come the rest of the components

For myself, I'd be happy if it was just a breakout board that suited the extra IO (at least some) of the Mega 2560.. I'm using a fair bit of them, and with no decent headers for them it is a little bit haywire in there... especially when I need pullup resistors on the analog IO's for temperature sensors.

Looking into the SPI quad thermocouple board on fleabay for compressor, intake, and EGT.. a bit of money with my crap exchange rate but would simplify a lot of stuff.

I've added jumpers to the perf/cruise/brake io's at the top right in case you want to reassign the pins, and remove the 10k pullups (ya ya I know the arduino can do its own pullup but I don't see a reason to be reliant on that)

Bottom right is the bluetooth, very common HC-05, with a jumper for the 3.3v rail for programming it

Thoughts ? Board is almost outa room

AMP2 Corinthians 8:21For we take thought beforehand and aim to be honest and absolutely above suspicion, not only in the sight of the Lord but also in the sight of men.

I would really like to see at least some through-holes for the A6 and A7 on the mega, since it's pretty much impossible to hook anything onto them with most shields there.. That way you or anyone else could make a shield that is specifically for the extra IO's on the Mega...

And BTW. you got TONS of room left. Have you got an interrupt enabled IO broken out for engine RPM sense? (D2, D3)

Are you counting engine rpm right now ? I thought you were just square waving it on a spare d_io ? Do you need an interrupt pin ?

I had to abandon the headers to make room for the bluetooth and pin headers, a stacked header won't fit in the case I'm trying to put this in anyways. But I already have decided on making a lil and big bb ;-)

AMP2 Corinthians 8:21For we take thought beforehand and aim to be honest and absolutely above suspicion, not only in the sight of the Lord but also in the sight of men.

For engine RPM I would need an externally accessible interrupt pin, and I use one for the turbine shaft speed as well rather than Freqmeasure... The ISR's are very short, they're just an incrementer, so it's just i++;, and the speed calculation is done elsewhere

I take the tach signal from the Engine ECU, which is a nicely formatted square wave of 5V already, so it doesn't need any filtering.. I was contemplating adding vehicle speed sensing as well, just haven't gotten to it yet, I'm not sure if there's a preconditioned signal for me to tap into or if I have to do the filtering.. the VSS gets 8V power (weird, yeah), and I haven't checked to see what the peak voltage is from it.. perhaps just a step-down resistor bridge would be sufficient.